package com.eatme.core.map;

import java.util.ArrayList;
import java.util.Random;

public class LinkedListMap<K,V> implements Map<K,V> {

    private class Node {

        public K key;

        public V value;

        private Node next;

        public Node(K key,V value,Node next) {
            this.key = key;
            this.value =value;
            this.next = next;
        }

        public Node(K key) {
            this(key,null,null);
        }

        public Node() {
            this(null,null,null);
        }

        @Override
        public String toString() {
            return key.toString()+" : "+value.toString();
        }


    }

    private Node dummyHead;

    private int size;

    public LinkedListMap() {
        dummyHead = new Node();
        size = 0;
    }

    @Override
    public void add(K key, V value) {
        Node node = getNode(key);
        if (node==null){
            dummyHead.next = new Node(key,value,dummyHead.next);
            size++;
        }else
            node.value = value;
    }

    @Override
    public V remove(K key) {
        Node prev = dummyHead;
        while (prev.next!=null) {
            if (prev.next.key.equals(key))
                break;
            prev = prev.next;
        }
        if (prev.next!=null) {
            Node delNode = prev.next;
            prev.next = delNode.next;
            delNode.next = null;
            size--;
            return delNode.value;
        }
        return null;
    }

    @Override
    public boolean contains(K key) {
        return getNode(key) != null;
    }

    @Override
    public V get(K key) {
        Node node = getNode(key);
        return node == null ? null: node.value;
    }

    @Override
    public void set(K key, V newValue) {
        Node node = getNode(key);
        if (node==null){
            throw new IllegalArgumentException(key +"doesn't exist.");
        }else
            node.value = newValue;

    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    private Node getNode(K key) {
        Node cur = dummyHead.next;
        while (cur!=null) {
            if (cur.key.equals(key))
                return cur;
            cur = cur.next;
        }
        return null;
    }

    public static void main(String[] args) {
        ArrayList<Integer> arrayList = new ArrayList<>();
        Random random = new Random();
        for (int i = 0; i < 1000; i++) {
            arrayList.add(random.nextInt(1000));
        }
        System.out.println("arraylist size:"+arrayList.size());
        LinkedListMap<Integer,Integer> map = new LinkedListMap<>();
        for (int i = 0; i < arrayList.size(); i++) {
            if (map.contains(arrayList.get(i)))
                map.set(arrayList.get(i),map.get(arrayList.get(i))+1);
            else
                map.add(arrayList.get(i),1);

        }

        System.out.println("Total different numbers: " +map.getSize());
        System.out.println("Frequency of 1: " +map.get(1));



    }

}
